He's the guy responsible for making lame movies almost good by creating a great atmosphere. By 2020, he'll be up there with John Williams, Alan Silvestri, James Newton Howard, Hans Zimmer and Ennio Morricone. As close as a Composer can get to a "household name."
Birth, Hostage, Lust Caution, The Curious Case of Benjamin Button as well as a billion solid French movies like Nid de guepes (The Nest). They weren't great movies, were they? But there was maybe something about them that drew you in and kept you watching? Yeah, that's a good way to recognize a Desplat score.
Also, his name has the word "splat" in it. Thus, he is already in Epic Win territory by default.
Hmm, Not Sold. I Can Look Out For Further Proof?
You can. Wes Anderson's 'Fantastic Mr Fox' and 'Twilight: New Moon' are on the horizon.